1. Field of the Invention
The present invention relates to mutant microorganisms having the ability to produce propanol in high concentration and high yield, and to a method of producing propanol using the same. More particularly, the present invention relates to mutant microorganisms having the ability to produce propanol in high concentration and high yield, which have introduced therein genes that encodes enzymes which are involved in the biosynthesis of propanol from threonine, and to a method of producing propanol using the same.
2. Background of the Related Art
Due to high oil prices and environmental concerns, the microbial production of biodiesel is attracting a great deal of attention. As biodiesel has been considered as an alternative fuel, which can substitute for diesel oil or used in a mixture with diesel oil in diesel engines, the market size thereof has increased rapidly. In the European Union (EU) in 2008, biodiesel was produced in an amount of 660 million tons and reached a market size of 5.5 billion euro.
In recent years, as propanol has been considered as an alternative fuel for gasoline, the market size thereof has increased rapidly. Currently, 10 to 12 billion pounds of propanol are being produced annually in the world (Lee, S. Y. et al., Biotechnology and Bioengineering 101: 209, 2008). Particularly, biopropanol has properties suitable as fuels, including suitable energy density, controllable volatility, sufficient octane number, low impurity content and the like, and it has advantages over ethanol in that it has higher energy efficiency, is more easily mixed with gasoline and can be used in existing oil pipelines or automotive engines.
The production of 1 g/L of propanol in wild-type E. coli was reported (Atsumi, S. et al, Directed evolution of Methanococcus jannaschii citramalate synthase for biosynthesis of 1-propanol and 1-butanol by Escherichia coli. Appl Environ Microbiol, 74:7802-7808, 2008), but this amount of production is insufficient for industrial applications, and the activities of genes introduced into the strain are low and thus need to be further improved.
Therefore, it is believed that producing increased amounts of propanol using strains developed using metabolic engineering or omics technology is required to replace fossil fuels which are being exhausted.
Accordingly, the present inventors have made extensive efforts to increase the efficiency of production of propanol, and as a result, have identified genes that encode enzymes involved in the biosynthesis of propanol from threonine, and have constructed mutant microorganisms having introduced therein these genes, and also have found that these mutant microorganisms have a high ability to produce propanol, compared to existing mutant microorganisms, thereby completing the present invention.